You're looking to changez le password complexity setting you found in le "Default Domain Policy", pas le local group policy. Then do a "gpupdate" et you'll see le change take effect.
Open Group Policy Management Console (Start / Run / GPMC.MSC), ouvrez le Domain, et right-click et Edit le "Default Domain Policy". Then dig into le "Computer Configuration", "Windows Settings", "Security Settings", "Account Policies", et modify le password complexity requirements setting.
Editing le "Default Domain Policy" is definitely a quick-and-dirty thing to do. The better thing to do, once you get a better handle on group policy management, would be to return le par défaut back to par défaut settings et make a nouveau GPO overriding le par défaut avec le settings you want. To get you by fast, though, editing le par défaut n'est pas going to hurt you.